JP2010034393A - Method of controlling substrate treatment and storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of controlling substrate treatment, which can strictly control the dimensions of shapes of minute structures even when a substrate has two types of minute structures. <P>SOLUTION: A spectrum of reflectivity from a memory cell 83 is calculated and acquired by using RCWA for every CD value of the memory cell 83; a spectrum of reflectivity from a logic part 82 is calculated and acquired by using a scalar analysis; reference spectrum data are acquired for every CD value of the memory cell 83 by superposing the two spectra of reflectivity; measured spectrum data are calculated based on reflected light from the memory cell 83 and the logic part 82 during etching; a CD value of the reference spectrum data nearly coincident with the measured spectrum data is acquired as a measured CD value of the memory cell 83; and etching is ended when the measured CD value reaches a desired value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a substrate processing control method and a storage medium, and more particularly to a substrate processing control method when a predetermined processing is performed on a substrate on which a minute line and space structure is formed.

  Usually, when manufacturing a semiconductor device from a wafer as a substrate, a line and space structure is formed by etching.

  FIG. 7 is a diagram showing a typical example of a process for forming a line and space structure by etching, and FIGS. 7A and 7B are processes for forming a line and space structure in an antireflection film. 7 (C) and 7 (D) are line and space structure forming steps in the photoresist film.

  7A and 7B, a base film 72, an antireflection film (BARC film) 73, and a pattern structure that partially exposes the antireflection film 73 are sequentially stacked on the silicon base 71. In the wafer having the photoresist film 74, the exposed BARC film 73 is etched using the photoresist film 74 as a mask. At this time, the BARC film 73 is etched not only in the thickness direction (vertical direction in the figure) but also in the width direction (horizontal direction in the figure), and as a result, a plurality of narrow lines composed of the remainder of the BARC film 73 on the base film 72. 75 is formed.

  7C and 7D, in a wafer having a base film 77, an organic film 78, a SiARC film 79, and a photoresist film 80 having a predetermined pattern structure, which are sequentially stacked on the silicon base 76. Only the photoresist film 80 is etched. At this time, the photoresist film 80 is etched not only in the thickness direction but also in the width direction. As a result, a plurality of narrow lines 81 made of the remaining portion of the photoresist film 80 are formed on the SiARC film 79.

  In recent years, with the progress of miniaturization of semiconductor devices, the required processing dimensions have been further miniaturized, and further higher processing accuracy has been demanded. For example, in a line-and-space structure formed by etching, the line width (Critical Dimension value, hereinafter referred to as “CD value”) is different from the desired value by several nm, and the desired performance cannot be exhibited in the semiconductor device. Therefore, it is required to strictly control the CD values of the lines 75 and 81 during etching.

  However, the etching in FIGS. 7A and 7B is terminated when the BARC film 73 is partially etched and the base film 72 is exposed, and the etching in FIGS. 7C and 7D is performed. Is terminated when a preset etching time has elapsed. That is, the etching is completed without measuring the dimensions related to the line. Therefore, the CD values of the lines 75 and 81 cannot be strictly controlled.

  In view of this, a method has been proposed in which a dimension related to a line is measured using reflected white light, and etching is controlled based on the measurement result. For example, a measurement line-and-space structure is formed by etching under predetermined processing conditions at a position where measurement is easy on a test wafer, a CD value of the formed line-and-space structure is measured, and the measured CD The method of changing the etching processing conditions based on the value (feedback method), the dimension of the shape of the pattern structure of the photoresist film on the wafer before etching is measured, and the etching processing is performed based on the measured dimension A method of changing conditions (feed forward method) is adopted.

  However, since the dimensions of the formed line are not directly measured in any of the feedback method and the feedforward method described above, there is still a problem in quality assurance. In addition, each method has a problem that the throughput is lowered because the measurement is performed by an apparatus dedicated to measurement.

  On the other hand, a method is known in which the thickness of the mask layer is monitored (measured) during etching of the layer to be etched, and the etching is terminated when the monitored thickness reaches a predetermined thickness (for example, , See Patent Document 1). In this method, based on the fact that the interference of the reflected light from the surface of the mask layer and the reflected light from the interface between the mask layer and the silicon layer changes depending on the film thickness of the mask layer, these are irradiated with light on the wafer. The reflected light is detected, the spectral reflectance (reflectance spectrum) of a plurality of wavelengths is obtained, and the film thickness of the mask layer is measured based on a calibration curve (reflectance spectrum) prepared in advance.

In a fine line-and-space structure corresponding to miniaturization of required processing dimensions, a plurality of lines having the same CD value are arranged at equal intervals, but the CD value and space width of each line are reduced to about several tens of nm. Therefore, this minute line and space structure forms a diffraction grating. In the diffraction grating, when the grating width corresponding to the CD value of the line changes, the reflected light causes a phase shift and becomes a diffracted wave. A shift occurs and the reflectance spectrum changes. Therefore, if the method of Patent Document 1 described above is applied, it is considered that it is easy to directly control the etching by directly measuring the line dimension, that is, to strictly control the CD value of the line in the etching.
JP 2006-86168 A

  However, in order to prevent a decrease in throughput, it is necessary to provide a monitoring device for reflected light in the etching apparatus in order to measure the reflected light with the etching apparatus. Since the etching apparatus has a complicated configuration, the installation place of the monitor apparatus is limited. Therefore, the monitor device cannot be moved to a position suitable for measuring reflected light from a minute line and space structure on the wafer.

  Further, a chip as a semiconductor device usually has two kinds of minute line and space structures as shown in FIG. The line and space structure with a relatively large (sparse) pitch of each line is the logic unit 82, and the line and space structure with a relatively small (fine) pitch of each line is the memory cell 83, as described above. Since the monitor device cannot be moved to the limit, the chip on the wafer cannot be brought close to the limit, and the spot diameter of the irradiation light from the monitor device becomes large. Irradiation light may be irradiated. In some cases, the monitor device cannot be arranged so that only the reflected light from the memory cell 83 is received with the monitor device facing only the memory cell 83. As a result, the monitor device may receive not only the reflected light of the memory cell 83 but also the reflected light from the logic unit 82.

  The method of Patent Document 1 described above detects reflected light from a mask film having a single film thickness, and detects reflected light from a mask film in which a plurality of film thicknesses are mixed. Therefore, even if the method of Patent Document 1 is applied to a chip in which reflected light is generated from both the logic unit 82 and the memory cell 83, a plurality of received reflected lights are not considered. Will be compared with a calibration curve prepared in advance in consideration of detection of reflected light from a single line-and-space structure, but with the above spectral reflectance and a calibration curve prepared in advance, Since the number of premise line and space structures is different, it is impossible to make an accurate comparison. Therefore, it is difficult to strictly control the CD value of a line having a line and space structure in etching.

  An object of the present invention is to provide a substrate processing control method and a storage medium capable of strictly controlling the size of a shape in a microstructure even when the substrate has two types of microstructures.

  In order to achieve the above object, the substrate processing control method according to claim 1 is characterized in that the first microstructure having a shape with a size less than or equal to the wavelength of the irradiated light and a shape with a size greater than or equal to the wavelength of the irradiated light. A substrate processing control method for controlling the predetermined substrate processing in a substrate processing apparatus for performing a predetermined substrate processing in which the dimension of the shape of the first microstructure changes on a substrate having a second microstructure having a surface formed thereon A spectrum of the first reflectance in the reflected light from the first microstructure and a spectrum of the second reflectance in the reflected light from the second microstructure when the dimension of the shape is changed. A reflectance spectrum calculation step for preliminarily calculating and acquiring the dimensions of each of the shapes, and superimposing the acquired first reflectance spectrum and the acquired second reflectance spectrum. Reflectance spectrum superimposing step for obtaining reference spectrum data on the size of the shape, and measuring reflected light from the first and second microstructures of the substrate while irradiating the substrate with light, The reflectance spectrum measurement step for obtaining the reflectance spectrum of the reflected light as measured spectrum data, and comparing the measured spectrum data with each of the reference spectrum data and corresponding to the reference spectrum data that is closest to the measured spectrum data A shape dimension calculating step for calculating the dimension of the shape to be measured as the dimension of the shape to be measured, and a substrate processing end for ending the predetermined substrate processing when the calculated shape dimension reaches a desired value A step of calculating the reflectance spectrum, The spectrum of the first reflectance is obtained from the reflected light from the first microstructure using RCWA, and the second reflectance is obtained from the reflected light from the second microstructure using scalar analysis. A spectrum is acquired.

  The substrate processing control method according to claim 2 is the substrate processing control method according to claim 1, wherein, in the reflectance spectrum superimposing step, the first microstructure and the second microstructure are present according to a ratio of the first microstructure and the second microstructure. The acquired first reflectance spectrum and the acquired second reflectance spectrum are superimposed.

  The substrate processing control method according to claim 3 is the substrate processing control method according to claim 1 or 2, wherein the first microstructure and the second microstructure do not overlap on the surface of the substrate. To do.

  The substrate processing control method according to claim 4 is the substrate processing control method according to any one of claims 1 to 3, wherein a diameter of the irradiated light on the surface of the substrate is 20 mm or more. Features.

  In order to achieve the above object, the storage medium according to claim 5 is a first microstructure having a shape with a size less than or equal to the wavelength of the irradiated light and a shape having a shape with a size greater than or equal to the wavelength of the irradiated light. A substrate processing control method for controlling the predetermined substrate processing in a substrate processing apparatus for performing a predetermined substrate processing in which the size of the shape of the first microstructure changes on a substrate having two microstructures formed on the surface thereof A computer-readable storage medium storing a program to be executed by the substrate processing control method, wherein the substrate processing control method has a first reflectance of reflected light from the first microstructure when the shape dimension changes. A reflectance spectrum calculation step in which the spectrum and the spectrum of the second reflectance in the reflected light from the second microstructure are calculated in advance for the dimensions of the shapes. A reflectance spectrum superimposing step of superimposing the acquired first reflectance spectrum and the acquired second reflectance spectrum to obtain reference spectrum data for each dimension of the shape; Reflectance spectrum measurement in which reflected light from the first and second microstructures of the substrate is measured while irradiating the substrate, and a reflectance spectrum of the measured reflected light is obtained as measured spectrum data. A step of comparing the measured spectrum data with each of the reference spectrum data, and calculating a dimension of the shape corresponding to the reference spectrum data closest to the measured spectrum data as a dimension of the measured shape Dimension calculation step and when the calculated shape dimension reaches a desired value A substrate processing end step for ending the predetermined substrate processing, and in the reflectance spectrum calculation step, the spectrum of the first reflectance is calculated from the reflected light from the first microstructure using RCWA. And acquiring a spectrum of the second reflectance from the reflected light from the second microstructure using a scalar analysis.

  According to the substrate processing control method according to claim 1 and the storage medium according to claim 5, the first reflectance of the reflected light from the first microstructure when the size of the shape is changed by the predetermined substrate processing. The spectrum and the spectrum of the second reflectance in the reflected light from the second microstructure are obtained by calculating in advance for the dimensions of each shape, and the obtained two spectra of the reflectance are superimposed to obtain each shape. After obtaining the reference spectrum data for the dimensions, the spectrum of the reflectance in the measured reflected light from the first and second microstructures is obtained as the measured spectrum data, and the reference spectrum data closest to the measured spectrum data is obtained. The corresponding shape dimension is calculated as the measured shape dimension, and the calculated shape dimension reaches the desired value. To end the substrate processing. In the measured spectrum data, the spectrum of the first reflectance and the spectrum of the second reflectance are superimposed, but also in each reference spectrum data, the spectrum of the first reflectance and the spectrum of the second reflectance are superimposed. As a result, the number of microstructures assumed by the measured spectrum data and each reference spectrum data is the same, which makes it possible to accurately compare the measured spectrum data and each reference spectrum data. In addition, when a spectrum is used, the overlap of reflected light can be expressed by the sum of a plurality of spectra, so that the accuracy of each calculated reference spectrum data can be improved. As a result, even when the substrate has the first microstructure and the second microstructure, that is, two types of microstructures, the dimension of the shape in the microstructure can be accurately measured. The size of the shape in the structure can be strictly controlled.

  Further, in the reflectance spectrum calculation step, the spectrum of the first reflectance is acquired from the reflected light from the first microstructure having a shape having a size equal to or smaller than the wavelength of the irradiated light by using RCWA, and is irradiated. The spectrum of the second reflectance is acquired from the reflected light from the second microstructure having a shape with a dimension equal to or larger than the wavelength of the light to be obtained using scalar analysis. Reflected light from a shape with a size less than the wavelength of the irradiated light cannot be accurately analyzed using scalar analysis, but can be accurately analyzed using RCWA. On the other hand, since scalar analysis is simpler than RCWA, analysis time is short. Therefore, by properly using RCWA and scalar analysis, the accuracy of each reference spectrum data can be further improved, and the time required for obtaining each reference spectrum data can be prevented from becoming unnecessarily long.

  According to the substrate processing control method according to claim 2, the acquired spectrum of the first reflectance and the acquired second reflectance in accordance with the existence ratio of the first microstructure and the second microstructure. Therefore, the accuracy of each reference spectrum data can be further improved.

  According to the substrate processing control method of the third aspect, since the first microstructure and the second microstructure do not overlap on the surface of the substrate, the reflected light from the first microstructure and the second microstructure can be used. The reflected light does not interfere. As a result, the measured spectrum data is a reflectance spectrum of the reflected light obtained by superimposing the reflected light from the first microstructure and the reflected light from the second microstructure. Therefore, the measured spectrum data has the first reflectance. The spectrum and the second reflectance spectrum can be accurately compared with the superimposed reference spectrum data, so that the shape dimensions in the microstructure can be measured more accurately.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, a substrate processing apparatus to which a substrate processing control method according to an embodiment of the present invention is applied will be described. This substrate processing apparatus is configured to perform etching using plasma on a semiconductor wafer (hereinafter simply referred to as “wafer”) W as a substrate. In the substrate processing apparatus 10, logic portions 82 and memory cells 83 having a line and space structure as shown in FIG. 8 are formed on the surface of the wafer W. In this wafer W, the memory cell 83 and the logic unit 82 do not overlap on the surface of the wafer W.

  FIG. 1 is a cross-sectional view schematically showing a configuration of a substrate processing apparatus to which the substrate processing control method according to the present embodiment is applied.

  In FIG. 1, a substrate processing apparatus 10 includes, for example, a processing chamber 11 made of a conductive material such as aluminum, a lower electrode 12 disposed on the bottom surface of the processing chamber 11 as a mounting table on which a wafer W is mounted, And a shower head 13 disposed above the lower electrode 12 at a predetermined interval.

  An exhaust unit 14 connected to a vacuum exhaust device (not shown) is connected to the lower part of the processing chamber 11, and a high frequency power supply 16 is connected to the lower electrode 12 via a matching unit 15, and a buffer inside the shower head 13. A processing gas introduction pipe 18 is connected to the chamber 17, and a processing gas supply device 19 is connected to the processing gas introduction pipe 18. The lower portion of the shower head 13 has a plurality of gas holes 20 that allow the buffer chamber 17 to communicate with the processing space S that is a space between the shower head 13 and the lower electrode 12. The shower head 13 supplies the processing gas introduced into the buffer chamber 17 from the processing gas introduction pipe 18 into the processing space S through the plurality of gas holes 20.

  In the substrate processing apparatus 10, after the processing chamber 11 is depressurized to a predetermined degree of vacuum by the exhaust unit 14, the processing is performed from the shower head 13 to the processing space S in a state where a high frequency voltage is applied from the lower electrode 12 to the processing space S. Gas is supplied, and plasma is generated from the processing gas in the processing space S. The generated plasma etches the etched layers 85 a and 85 b of the wafer W that are not covered by the mask films 84 a and 84 b, thereby forming the logic portion 82 and the memory cell 83.

  The shower head 13 in the processing chamber 11 is provided with a monitor device 21 for observing the wafer W placed on the lower electrode 12 from above. The monitor device 21 is made of a cylindrical member and penetrates the shower head 13. A window member 22 made of a transparent material such as quartz glass is provided at the upper end of the monitor device 21. In addition, an optical fiber 24 is disposed above the processing chamber 11 so as to face the upper end of the monitor device 21 via a condenser lens 23.

  The optical fiber 24 is connected to a CD value measuring device 25 that measures the line width (CD value) of the memory cell 83. The CD value measuring device 25 includes a white light source 26 and a spectroscopic unit 27 connected to the optical fiber 24, a light detection unit 28 connected to the spectroscopic unit 27, and a calculation unit 29 connected to the photodetection unit 28. And a storage unit 30 connected to the calculation unit 29, and operate under the control of a controller (not shown) of the substrate processing apparatus 10. As the white light source 26, for example, Xe flash lamp light or halogen lamp light is used. For example, a prism is used as the spectroscopic unit 27. The controller is connected not only to the CD value measuring device 25 but also to each component of the substrate processing apparatus 10, for example, the high frequency power supply 16, and controls the operation of each component.

  In the CD value measuring device 25, the white light source 26 irradiates white light toward the wafer W on the lower electrode 12 through the optical fiber 24, the condenser lens 23, and the monitor device 21, and the spectroscopic unit 27 emits light from the wafer W. The reflected light is received through the optical fiber 24 or the like. Further, the spectroscopic unit 27 splits the received reflected light for each wavelength, and the light detection unit 28 detects the reflectance of the reflected light for each wavelength, converts the reflectance at each wavelength into an electrical signal, and outputs it to the arithmetic unit 29. Send. The calculation unit 29 calculates the reflectance spectrum as the measured spectrum data shown in FIG. 2 based on the received electrical signal, and compares the measured spectrum data with reference spectrum data described later stored in the storage unit 30 in advance. The CD value of the memory cell 83 is measured.

  In order to strictly control the CD value of the memory cell 83, it is necessary to measure the CD value of the memory cell 83 during etching. Here, the CD value of the memory cell 83 and the width of the space are about several tens of nm in order to meet the recent miniaturization of required processing dimensions. Therefore, the memory cell 83 functions as a diffraction grating when irradiated with white light. In the diffraction grating, when the grating width corresponding to the CD value of the line changes, the reflected light causes a phase shift. Therefore, when the CD value of the memory cell 83 changes, the reflected light from the memory cell 83 also causes a phase shift. The reflectivity of each wavelength changes in. That is, when the CD value of the memory cell 83 changes, the reflectance spectrum also changes.

  Therefore, as shown in FIG. 3, if the reflectance spectrum is calculated in advance for each CD value by simulation and acquired as reference spectrum data, the measured reflectance spectrum (measured spectrum data) (FIG. 2) And the reference spectrum data of each CD value (each data in FIG. 3), the CD value of the memory cell 83 can be calculated during etching. Specifically, the CD value of the reference spectrum data that substantially matches the measured spectrum data is calculated as the CD value of the memory cell 83.

  Incidentally, as described above, in the substrate processing apparatus 10, the installation location of the monitor device 21 is limited. Therefore, the spot diameter of white light from the white light source 26 on the surface of the wafer W is about 20 mm. It cannot be arranged to face only the memory cell 83. As a result, not only the reflected light from the memory cell 83 but also the reflected light from the logic unit 82 may be superimposed on the reflected light received by the spectroscopic unit 27.

  In this case, it is necessary to consider the superimposition of the reflected light also in each reference spectrum data. In other words, since the number of line and space structures assumed by the measured spectrum data is 2, in order to compare the reference spectrum data with the measured spectrum data, the number of line and space structures assumed by the reference spectrum data is 2 is required.

  In the present embodiment, corresponding to this, when the reference spectrum data is calculated and obtained in advance for each CD value by simulation, not only the reflectance spectrum for each CD value from the memory cell 83 but also the logic unit 82. The spectrum of the reflectance from is calculated and the spectrum of these reflectances is superimposed.

  Further, although the CD value of the memory cell 83 is several tens of nm, the wavelength of the white light to be irradiated is several hundred nm, and therefore the CD value of the memory cell 83 is equal to or less than the wavelength of the white light to be irradiated. Therefore, the CD value of the memory cell 83 is smaller than most of the wavelength of the reflected light from the memory cell 83. On the other hand, since the width of the line and the width of the space in the logic unit 82 are several thousand nm, the width of the line in the logic unit 82 is equal to or greater than the wavelength of the irradiated white light. Therefore, the width of the line in the logic unit 82 is larger than most of the wavelengths of reflected light from the logic unit 82.

  Generally, in the (frequency) analysis of a diffracted wave, if the dimension of the measurement object is equal to or greater than the wavelength of the diffracted wave, a scalar analysis that can be performed based only on the reflectance and the optical path difference can be used. If the dimensions are less than or equal to the wavelength of the diffracted wave, scalar analysis cannot be used, and RCWA (Rigorous Coupling Wave Analysis), which is an exact electromagnetic calculation, must be used (US patent application for RCWA) No. 09 / 770,997 (refer to “Caching of Interpolation Calculations in Strictly Coupled Wave Analysis”). RCWA can be used even when the dimension of the measurement object is less than or equal to the wavelength of the diffracted wave, but RCWA requires a long time for calculation because the vector eigenvalue is obtained.

  Therefore, in the present embodiment, in the acquisition of the reference spectrum data for each CD value, the reflectance spectrum of the reflected light from the memory cell 83 (hereinafter referred to as “the reflectance spectrum from the memory cell 83”) (first). RCWA is used when calculating and obtaining 1 (reflectance spectrum of 1), and the spectrum of the reflectance with respect to the reflected light from the logic unit 82 (hereinafter referred to as “reflectance spectrum from the logic unit 82”) (first). Scalar analysis is used when calculating and obtaining the (reflectance spectrum of 2).

  Further, when both the memory cell 83 and the logic unit 82 exist in the white light spot on the surface of the wafer W, the existence ratio of the logic unit 82 and the memory cell 83 is formed on the surface of the wafer W. Varies depending on the type of chip. When the presence ratio of the logic unit 82 and the memory cell 83 changes, the ratio between the amount of reflected light from the logic unit 82 and the amount of reflected light from the memory cell 83 in the reflected light received by the spectroscopic unit 27 changes. That is, the measured spectrum data changes according to the change in the existence ratio of the logic unit 82 and the memory cell 83. Therefore, it is necessary to consider the change in the existence ratio of the logic unit 82 and the memory cell 83 also in the reference spectrum data.

In the present embodiment, in response to this, when the reference spectrum data is acquired in advance by simulation, the reflectance spectrum from the memory cell 83 is not simply added to the reflectance spectrum from the memory cell 83, and the spot spectrum data is obtained. Are overlapped according to the existence ratio of the logic part 82 and the memory cell 83 in Specifically calculating each reference spectrum data S _R by the following equation (1).

I _M is the reflectance from the memory cell 83 at each wavelength, I _L is the reflectance from the logic portion 82 at each wavelength, f is the existence ratio (%) of the memory cells 83 in the spot, 100-f logic unit in the spot 82 is an abundance ratio (%). According to the above formula (1), for example, the existing ratio f is changed from 60% to 30%, as shown in FIG. 4, reference spectrum data S _R is the reference when only the logic unit 82 in the spot is present It changes so as to approach the spectrum data. In the present embodiment, reference spectrum data at each existence ratio is obtained by changing the existence ratio of the memory cells 83 in the CD value of the same memory cell 83.

  As described above, the reference spectrum data acquired for each CD value of the memory cell 83 and for each existence ratio of the memory cell 83 is stored in the storage unit 30 at least before the start of etching.

  FIG. 5 is a flowchart of the etching control process as the substrate processing control method according to the present embodiment.

  In FIG. 5, first, a simulation model of the memory cell 83 or the logic unit 82 that is expected to be formed by etching in the spot of white light on the surface of the wafer W is created, and the simulation model is used. As described above, the reflectance spectrum from the memory cell 83 is calculated and obtained using RCWA for each CD value of the memory cell 83, and the reflectance spectrum from the logic unit 82 is calculated using scalar analysis. (Step S51) (reflectance spectrum calculation step), and further, the reflectivity from the memory cell 83 based on the above formula (1) for each existence ratio of the memory cell 83 with respect to the CD value of the same memory cell 83. And the spectrum of the reflectance from the logic unit 82 are used for the logic unit 82 and the spot in the spot. The reference spectrum data is obtained for each CD value of the memory cell 83 and for each existence ratio of the memory cell 83 by the superposition according to the existence ratio of the memory cell 83 (reflectance spectrum superposition step). Each reference spectrum data is stored in the storage unit 30 (step S52).

  Next, etching of the wafer W is started in the substrate processing apparatus 10 (step S53). Further, the white light source 26 irradiates white light toward the wafer W, and the spectroscopic unit 27 performs the memory cell 83 and logic in the white light spot. The reflected light from the unit 82 is received (step S54), and the spectroscopic unit 27 and the calculation unit 29 divide the received reflected light for each wavelength to calculate actual spectrum data (step S55) (reflectance spectrum actual measurement step). ).

  Next, the calculation unit 29 compares the calculated actual spectrum data with each reference spectrum data stored in the storage unit 30, and determines the CD value of the reference spectrum data that substantially matches the actual measurement spectrum data as the estimated CD value of the memory cell 83. It is calculated as (dimension of the shape to be measured) (step S56) (geometry dimension calculation step).

  Here, since the calculated estimated CD value is a value calculated from the reference data based on the simulation model, an error may occur between the estimated CD value and the actual CD value. In the present embodiment, in response to this, prior to the start of etching, a correlation (FIG. 6) between the estimated CD value and the actual CD value is obtained using another wafer W or the like, and the correlation is used. The estimated CD value is corrected, and the corrected estimated CD value is acquired as the measured CD value (step S57).

  Next, in step S58, the controller determines whether or not the measured CD value has reached the desired value. If the measured CD value has not reached the desired value, the controller returns to step S54 and measured. When the CD value reaches the desired value, the etching of the wafer W is finished (step S59) (substrate processing end step), and then this process is finished.

  According to the etching control process of FIG. 5, in the measured spectrum data, the reflectance spectrum from the memory cell 83 and the reflectance spectrum from the logic unit 82 are superimposed. Therefore, the number of the line-and-space structures assumed by the measured spectrum data and each reference spectrum data is the same. It is possible to accurately compare the data and each reference spectrum data. In addition, when a spectrum is used, the overlap of reflected light can be expressed by the sum of a plurality of spectra, so that the accuracy of each calculated reference spectrum data can be improved. As a result, even if the wafer W has the memory cell 83 and the logic unit 82, that is, two types of line and space structures, the CD value of the memory cell 83 can be accurately measured. The CD value of 83 can be strictly controlled.

  In the etching control process of FIG. 5, the spectrum of the reflectance from the memory cell 83 is obtained from the reflected light from the memory cell 83 having a CD value equal to or less than the wavelength of the irradiated white light, using RCWA, and irradiation is performed. The spectrum of the reflectance from the logic unit 82 is acquired from the reflected light from the logic unit 82 having a line width equal to or greater than the wavelength of the white light to be obtained using scalar analysis. Reflected light from a shape with a size less than or equal to the wavelength of the irradiated white light cannot be accurately analyzed using scalar analysis, but can be accurately analyzed using RCWA. On the other hand, since scalar analysis is simpler than RCWA, analysis time is short. Therefore, by properly using RCWA and scalar analysis, the accuracy of each reference spectrum data can be further improved, and the time required for obtaining each reference spectrum data can be prevented from becoming unnecessarily long.

  Further, in the etching control process of FIG. 5, the reflectance spectrum from the memory cell 83 and the acquired reflectance spectrum from the logic section 82 are superimposed in accordance with the existence ratio of the memory cell 83 and the logic section 82. Since the reference spectrum data is acquired, the accuracy of each reference spectrum data can be further improved.

  Further, in the wafer W described above, the memory cell 83 and the logic part 82 do not overlap on the surface of the wafer W, so that the reflected light from the memory cell 83 and the reflected light from the logic part 82 do not interfere. As a result, the measured spectrum data is a reflectance spectrum in the reflected light in which the reflected light from the memory cell 83 and the reflected light from the logic unit 82 are superimposed. Therefore, the measured spectrum data is the reflectance spectrum from the memory cell 83 and It is possible to accurately compare the reflectance spectrum from the logic unit 82 with the superimposed reference spectrum data, so that the CD value of the memory cell 83 can be measured more accurately.

  The above-described etching control process of FIG. 5 is executed in order to strictly control the CD value of the line and space structure during etching, but the control target by the etching control process of FIG. 5 is not limited to this. The diameter of the hole formed by may be controlled strictly. Specifically, when two types of holes having different diameters exist in the spot of white light, the diameter of the hole having a diameter equal to or smaller than the wavelength of white light can be controlled strictly.

  The above-described etching control process in FIG. 5 is executed when two types of line and space structures exist in the spot of white light, but three or more types of line and space structures exist in the spot of white light. Can be applied in case. In this case, the reference spectrum data is obtained by superimposing the reflectance spectrum of the reflected light from each of the three or more types of line and space structures, and the reference spectrum data is compared with the actually measured spectrum data.

  In the above-described embodiment, the substrate to be etched in the substrate processing apparatus 10 is a semiconductor device wafer. However, the substrate to be etched is not limited to this, for example, an LCD (Liquid Crystal). It may be a glass substrate such as Display) or FPD (Flat Panel Display).

  Another object of the present invention is to supply a computer (for example, a controller) with a storage medium storing software program codes for realizing the functions of the above-described embodiments, and the computer CPU stores the program in the storage medium. It is also achieved by reading and executing the code.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program code and the storage medium storing the program code constitute the present invention.

  Examples of the storage medium for supplying the program code include RAM, NV-RAM, floppy (registered trademark) disk, hard disk, magneto-optical disk, CD-ROM, CD-R, CD-RW, DVD (DVD). -ROM, DVD-RAM, DVD-RW, DVD + RW) and other optical disks, magnetic tapes, non-volatile memory cards, other ROMs, etc., as long as they can store the program code. Alternatively, the program code may be supplied to the computer by downloading from another computer or database (not shown) connected to the Internet, a commercial network, a local area network, or the like.

  Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (operating system) running on the CPU based on the instruction of the program code. A case where part or all of the actual processing is performed and the functions of the above-described embodiments are realized by the processing is also included.

  Further, after the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. This includes the case where the CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

  The form of the program code may include an object code, a program code executed by an interpreter, script data supplied to the OS, and the like.

1 is a cross-sectional view schematically showing a configuration of a substrate processing apparatus to which a substrate processing control method according to an embodiment of the present invention is applied. It is a figure which shows the measured spectrum data used in the substrate processing control method concerning this Embodiment. It is a figure which shows the reference spectrum data used in the substrate processing control method which concerns on this Embodiment. It is a figure which shows the mode of the change of reference spectrum data when the abundance ratio of a memory cell and a logic part changes. It is a flowchart of the etching control process as a substrate processing control method concerning this embodiment. It is sectional drawing which shows the correlation of an estimated CD value and an actual CD value. FIGS. 7A and 7B are diagrams showing a typical example of a process for forming a line and space structure by etching, and FIGS. 7A and 7B are processes for forming a line and space structure in an antireflection film, and FIG. And 7 (D) are steps of forming a line and space structure in the photoresist film. It is sectional drawing which shows roughly the structure of the logic part and memory cell in the chip | tip as a semiconductor device.

Explanation of symbols

W Wafer 10 Substrate Processing Device 25 CD Value Measuring Device 27 Spectrometer 28 Photodetector 29 Computing Unit 30 Storage Unit 82 Logic Unit 83 Memory Cell

Claims (5)

A first microstructure having a shape with a dimension less than or equal to the wavelength of the irradiated light and a second microstructure having a shape with a dimension greater than or equal to the wavelength of the irradiated light are formed on the surface of the first microstructure. A substrate processing control method for controlling the predetermined substrate processing in a substrate processing apparatus for performing a predetermined substrate processing in which a dimension of a shape in a microstructure is changed,
The spectrum of the first reflectance in the reflected light from the first microstructure and the spectrum of the second reflectance in the reflected light from the second microstructure when the dimension of the shape changes is shown for each of the shapes. A reflectance spectrum calculation step for pre-calculating and obtaining dimensions;
A reflectance spectrum superimposing step of superimposing the acquired spectrum of the first reflectance and the acquired spectrum of the second reflectance to obtain reference spectrum data for each of the shape dimensions;
Reflectance spectrum measurement in which reflected light from the first and second microstructures of the substrate is measured while irradiating the substrate, and a reflectance spectrum of the measured reflected light is obtained as measured spectrum data. Steps,
A shape dimension calculating step of comparing the measured spectrum data with each of the reference spectrum data and calculating the dimension of the shape corresponding to the reference spectrum data that is closest to the measured spectrum data as the dimension of the shape to be measured. When,
A substrate processing end step for ending the predetermined substrate processing when the calculated shape dimensions reach a desired value;
In the reflectance spectrum calculation step, the spectrum of the first reflectance is obtained from the reflected light from the first microstructure using RCWA, and scalar analysis is performed from the reflected light from the second microstructure. And obtaining a spectrum of the second reflectance.   In the reflectance spectrum superimposing step, the acquired spectrum of the first reflectance and the acquired spectrum of the second reflectance according to the existence ratio of the first microstructure and the second microstructure. The substrate processing control method according to claim 1, wherein:   3. The substrate processing control method according to claim 1, wherein the first microstructure and the second microstructure do not overlap on the surface of the substrate.   The substrate processing control method according to claim 1, wherein a diameter of the irradiated light on the surface of the substrate is 20 mm or more. A first microstructure having a shape with a dimension less than or equal to the wavelength of the irradiated light and a second microstructure having a shape with a dimension greater than or equal to the wavelength of the irradiated light are formed on the surface of the first microstructure. A computer-readable storage medium for storing a program for causing a computer to execute a substrate processing control method for controlling the predetermined substrate processing in a substrate processing apparatus that performs predetermined substrate processing in which a dimension of a shape in a microstructure changes. The substrate processing control method includes:
The spectrum of the first reflectance in the reflected light from the first microstructure and the spectrum of the second reflectance in the reflected light from the second microstructure when the dimension of the shape changes is shown for each of the shapes. A reflectance spectrum calculation step for pre-calculating and obtaining dimensions;
A reflectance spectrum superimposing step of superimposing the acquired spectrum of the first reflectance and the acquired spectrum of the second reflectance to obtain reference spectrum data for each of the shape dimensions;
Reflectance spectrum measurement in which reflected light from the first and second microstructures of the substrate is measured while irradiating the substrate, and a reflectance spectrum of the measured reflected light is obtained as measured spectrum data. Steps,
A shape dimension calculating step of comparing the measured spectrum data with each of the reference spectrum data and calculating the dimension of the shape corresponding to the reference spectrum data that is closest to the measured spectrum data as the dimension of the shape to be measured. When,
A substrate processing end step for ending the predetermined substrate processing when the calculated shape dimension reaches a desired value;
In the reflectance spectrum calculation step, the spectrum of the first reflectance is obtained from the reflected light from the first microstructure using RCWA, and scalar analysis is performed from the reflected light from the second microstructure. And obtaining the spectrum of the second reflectance.

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